1. Field of the Invention
The present invention relates to a print control apparatus for processing print information written in a predetermined page description language by rendering the print information on a memory on a band unit basis, a data processing method for the print control apparatus, and a storage medium storing computer readable programs of the data processing method.
2. Related Background Art
There are a variety of applications which can be processed by an information processing apparatus such as a host computer. Such applications include computer aided design (CAD), computer graphics (CG), design, desk top publishing (DTP) in business, and multimedia. Data processed by such applications is output from a printer capable of printing data with high precision.
In processing print information requested by such applications, the printer analyzes page description language (PDL) data transmitted from a host computer, renders the data of one page on a full-paint memory, and print it out on a recording sheet.
In order to meet a need for saving the capacity of a memory, a rendering method through band control (hereinafter called a band process) has been used widely, in which print information is rendered on a small band memory at high resolution synchronously with a paper feed of a printer.
With this band process, received PDL data is classified into various types of data such as a character, line, polygon and image, and after the print data of one page is stored in the form of intermediate language (objects) containing, for example, rendering positions and information on bands to be rendered, it is printed out at high resolution.
If a memory for storing objects becomes full before all objects of one page are stored therein or if a prediction rendering time for rendering a specific band does not follow a paper eject speed, the operation mode is automatically changed to a full-paint mode of rendering the entire of one page in a memory. In this full-paint mode, the objects already stored are sequentially rendered at low resolution starting from the object of the first band. The object which was rendered and is now unnecessary is deleted from the memory. The space of this empty memory is assigned to the full memory to obtain the memory capacity of one page. After the data of one page is rendered, it is printed out on a recording sheet. This process of executing the full-paint mode at low resolution is called hereinafter a xe2x80x9cdegrade processxe2x80x9d.
If image data requiring a large capacity of a memory is supplied to a conventional printer, it is judged as memory-full and the full-paint mode is executed. However, in this full-paint mode, objects of characters and lines not directly related to the image data which consumes the memory are printed also at low resolution so that the performance of a print engine cannot be fully utilized.
If image objects are images binarized through error diffusion and are output at low resolution in the full-paint mode or output in a reduced size in response to a PDL data instruction at a low resolution, then the quality of images are greatly degraded.
The present invention has been made to solve the above problems. It is an object of the present invention to provide a print control apparatus wherein the data type of input print information written with a page description language is judged, and the print information is converted into intermediate language data while reducing the print information which occupies a large capacity of a memory resource, so that a rendering area of the memory resource in the unit of a band to be used by the print information is suppressed as much as possible from not being reserved frequently in the memory resource and that a rendering process in the unit of a band can be executed as many times as possible to obtain a high quality print. The invention also provides a data processing method for the print control apparatus and a storage medium storing programs readable by a computer.
A print control apparatus according to a first aspect of the invention comprises: judging means for judging the data type of print information by analyzing the print information which is written with a predetermined page description language and input via a predetermined communication medium from an information processing apparatus; converting means for converting the print information into different intermediate language data for each data type judged by the judging means; storage means for storing the intermediate language data converted by the converting means; rendering means for rendering the intermediate language data stored in the storage means into predetermined print data; and control means for switching between rendering modes to be executed by the rendering means, through judgements of whether the total capacity of the intermediate language data converted by the converting means exceeds a set capacity occupied by the storage means.
According to a second aspect of the invention, if the judging means judges that the data type of the input print information written with the predetermined page description language is image information, the converting means converts the image data in the print information into the intermediate language data after reducing the image information.
According to a third aspect of the invention, if the total capacity of the intermediate language data exceeds the set capacity, the control means causes the rendering means to render the intermediate language data in the unit of a page.
According to a fourth aspect of the present invention, if the total capacity of the intermediate language data does not exceed the set capacity, the control means causes the rendering means to render the intermediate language data in the unit of a predetermined band width.
According to a fifth aspect of the present invention, if the control means causes the rendering means to render the intermediate language data in the unit of a page, the rendering means renders after enlarging the intermediate language data reduced by the converting means.
According to a sixth aspect of the present invention, the converting means converts image information in the print information binarized through error diffusion into multivalue image data, changes the multivalue image data to low resolution, binarizes the multivalue image data of low resolution, and converts the binarized multivalue image data into the intermediate language data.
According to a seventh aspect of the present invention, upon a request of a reduction print of the input print information written with the predetermined page description language, the converting means converts image information in the print information binarized through error diffusion into multivalue image data, changes the multivalue image data to low resolution, binarizes the multivalue image data of low resolution, and converts the binarized multivalue image data into the intermediate language data.
A data processing method, according to an eighth aspect of the present invention, for a print control apparatus which analyzes print information written with a predetermined page description language and input via a predetermined communication medium from an information processing apparatus, comprises: a judging step of judging the data type of the print information; a reducing step of, if the data type of the print information is judged as image information, reducing the image information; a converting step of converting the reduced print information or the input print information into predetermined intermediate language data; a judging step of judging whether the total capacity of the converted intermediate language data exceeds a set capacity occupied by a rendering memory; a first rendering step of rendering the converted intermediate language data into print data in the unit of a page in accordance with the judgement results; and a second rendering step of rendering the converted intermediate language data into print data in the unit of a predetermined band width in accordance with the judgement results.
According to a ninth aspect of the present invention, if the image information is information binarized through error diffusion, the reducing step converts the binarized image information into multivalue image data, changes the multivalue image data to low resolution, and binarizes the multivalue image data of low resolution.
According to a tenth aspect of the present invention, a medium storing a computer readable program is provided, the program comprising: a judging step of judging the data type of the print information; a reducing step of, if the data type of the print information is judged as image information, reducing the image information; a converting step of converting the reduced print information or the input print information into predetermined intermediate language data; a judging step of judging whether the total capacity of the converted intermediate language data exceeds a set capacity occupied by a rendering memory; a first rendering step of rendering the converted intermediate language data into print data in the unit of a page in accordance with the judgement results; and a second rendering step of rendering the converted intermediate language data into print data in the unit of a predetermined band width in accordance with the judgement results.